Linear feed cutting apparatus and method

ABSTRACT

A method for automatically cutting a workpiece comprising the steps of moving a workpiece along its longitudinal axis, positioning a cutting blade by rotating the blade about a vertical axis, positioning the cutting blade by rotating about a bevel axis, and moving the blade into cutting contact with the workpiece, thereby cutting the workpiece at a compound angle. The method may also comprises positioning the blade along a transverse axis. Further steps may include moving the cutting blade along a transverse axis simultaneous to moving the workpiece along its longitudinal axis, thereby creating a scarf cut; sorting a finished workpiece; and marking the workpiece.

FIELD OF THE INVENTION

[0001] This invention relates, in general, to an apparatus for thecutting of wood components, namely, dimension lumber into finishedrafters having predetermined lengths and angles at the ends thereof, foruse in building construction. In particular, this invention relates toan apparatus, including a novel linear feed table and adjustable cuttingdevice, for processing workpieces into finished components for assembly,and to a computer control and program for controlling same.

BACKGROUND OF THE INVENTION

[0002] Most lumber used in the construction industry is known asdimension lumber, which the present invention is intended to use.Dimension lumber has opposite sides parallel, with adjacent sidesforming a right angle, and is generally known by the nominal dimensionsof the sides, e.g., 2×4, 2×6, 4×8, etc. The longer sides hereinafter arecalled “faces,” and the shorter sides are called “edges.” The pieces ofdimension lumber to be processed by the present invention are called“workpieces” herein and, after cutting or processing, are called“components,” e.g., rafters of several kinds, and webs and chords fortrusses.

[0003] There are three kinds of rafters with which the present inventionis primarily concerned:

[0004] 1. “regular” rafters:

[0005] those which intersect their support or supported members, i.e.plates or ridge beams, respectively, at right angles to the faces, butat an angle to the edges thereof;

[0006] 2. “jack” rafters:

[0007] those which, at one end, intersect at least one of their supportor supported members at something other than a right angle to each ofthe faces and edges of the rafter, requiring a cut at what is calledhereinafter a “compound” angle or a “bevel” cut on that end of therafter; and

[0008] 3. “hip” and “valley” rafters:

[0009] those which intersect their support or supported members wheretwo or more come together at an angle, requiring two cuts on that end ofthe rafter, one or both of which may be compound angles. The angle atwhich the support or supported members come together is often, but notalways, a right angle.

[0010]FIG. 2 illustrates each of these kinds of rafters.

[0011] The present invention is also useful in cutting all of the websand chords for a single truss in one operation. Typically, an individualcomponent for a number of trusses was made up at the same time, toreduce the amount of hand adjustment, and therefore cost, per component.Otherwise, it became very expensive to produce them for a single truss,since adjustments had to be made between the cutting of each differentcomponent. Alternately, workpieces were fed into a cutting apparatuslaterally, as opposed to linearly, as in the present invention. Lateralfeed assemblies allow for simultaneous cutting of the ends of theworkpieces, but are not as efficient where the saw blades must resetbetween each workpiece.

[0012] To lay out a roof structure, certain distances must be accuratelyknown:

[0013] 1. the distance between the outside edges of the double topplate;

[0014] 2. the vertical distance from the upper face of the top-plate tothe ridge line; and

[0015] 3. the inclined, or slant, distance between the outside edge ofthe double top plates and the ridge line.

[0016] It will help in understanding the following discussion to referto FIGS. 1A-C of the drawings herein, which disclose three typicalarrangements of rafters and their associated support or supportedmembers, and will help to illustrate the concepts of “measuring line”and “ridge line”;

[0017] 1. FIG. 1C discloses a rafter simply laid upon the double topplate and the ridge beam, without cutting the rafter, except perhaps fora small notch at the upper end where it rests on the ridge beam;

[0018] a. the “measuring line” runs along the lower edge of the rafter,and

[0019] b. the “ridge line” is at the bottom of the rafter where it meetsthe adjoining or complementary rafter.

[0020] 2. FIG. 1B discloses a rafter notched at both upper and lowerends to fit over the ridge beam and the double top plate, respectively.In this case:

[0021] a. the “measuring line” runs parallel to the rafter's lower edge,from the outer upper edge of the double top plates to the center line ofthe ridge beam above its upper edge; and

[0022] b. the “ridge line” is at the intersection of the two raftermeasuring lines.

[0023] 3. FIG. 1A discloses a rafter cut at both upper and lower ends torest against the face of the ridge beam and the upper face of the doubletop plate, and the lower edge of the rafter intersects the lower edge ofthe ridge beam and the inner edge of the double top plate. In this case:

[0024] a. the “measuring line” runs parallel to the lower edge of therafter, from the outer upper edge of the double top plates to the pointof intersection of the measuring line with the face of the ridge beam;and

[0025] b. the “ridge line” runs down the midpoint of the ridge beamintersecting the projection of the measuring line.

[0026] The first structure of FIG. 1C is an older method of constructionlittle used at the present time.

[0027] The second and third structures of FIGS. 1B AND 1A representmethods of construction which are more widely used at present.

[0028] Regular rafters, i.e., those on which the ends are cut at rightangles to the faces (or the edges), even though the ends may be cut atsomething other than a right angle to the edges (or the faces,respectively), do not present a great problem to manufacture, since thelength of a given rafter as measured on one face (or edge) is the sameas the length measured on the other face (or edge).

[0029] However, hip, valley, and jack rafters present a more difficultproblem of manufacture:

[0030] 1. since jack rafters have at least one end thereof cut at acompound angle, i.e., an angle both to the edges and to the faces, thelengths of opposite faces (and/or edges) thereof are unequal; and

[0031] 2. hip and valley rafters have at least one end which requirestwo cuts, both of which are at angles to the faces and edges, but whichare usually at right angles to each other (although not necessarily).Although the lengths on the faces may be equal, the length on themeasuring line will be different than both.

[0032] Present machinery for making cuts to produce composite orcompound angles on roof structure components still requires substantialhand labor in the set-up and/or operation of cutting equipment.

[0033] U.S. Pat. No. 4,545,274 teaches a means of tilting the axis oftravel of a saw blade to correspond to the complement of the roof slope,and then angling the saw blade to make the compound cut. Lumber is movedpast the cutting station in a sideways manner. A separate cuttingstation is required for cuts on the other end of the component and, tocut components of differing lengths, one of the cutting stations must bemovable in relation to the other, which takes time. Further, the cuttingprocess is not automatic.

[0034] U.S. Pat. No. 6,212,983 incorporated herein by reference, teachesa linear feed system where compound cuts are achieved by tilting thework surface supporting the workpiece. This requires automating andadjusting the work surface to be movable for compound cuts. Adjustingworkpieces of great length may prove cumbersome. An example of a lateralfeed assembly can be found in Shamblin, U.S. Pat. No. 5,943,239, whichis incorporated herein. Such a system employs four or more cutters andrequires more work space and added expense.

[0035] There is no known linear feed machinery presently available tosequentially and automatically make the cuts necessary to achievecompound angles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIGS. 1A-C are profile views of regular rafters as used in threetypical installings, disclosing the parameters which establish themeasuring and cutting points for the operation of the present invention.

[0037]FIG. 2 is an oblique view of a hip roof and its components,including rafters, showing the important structural relationshipsthereof.

[0038]FIG. 3 is an oblique view of a jack rafter, with the importantlines and angles indicated thereon.

[0039]FIG. 4 is a top view of the present invention, disclosing thearrangement of the various major elements thereof.

[0040]FIG. 5A is an orthogonal view of the cutting assembly in positionto make a compound or bevel cut;

[0041]FIG. 5B is an orthogonal view of the cutting assembly in a homeposition;

[0042]FIG. 5C is a front view of the cutting assembly;

[0043]FIG. 5D is a right elevational view of the cutting assembly;

[0044]FIG. 6 is a detail schematic elevational view of the feederassembly;

[0045]FIG. 7 is a detail elevational view of a component sorter;

[0046]FIG. 8 is a sample workpiece; and

[0047]FIG. 9 is a schematic showing operation of the cutting assembly tocreate a scarf cut.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0048] The present invention is an apparatus for making roof structureand other components from dimension lumber workpieces by making therequired cuts in a sequential manner. Components such as hip, valley,and jack rafters, and webs and chords for trusses, are easily obtained.

[0049] As stated earlier, hereinafter “workpiece” refers to theunprocessed, or partially processed pieces of dimension lumber, while“component” refers only to the finished piece, after all processing hasbeen performed.

[0050] It will be helpful to refer to FIGS. 1-3, in understanding thefollowing preliminary description.

[0051] Regular rafters, as disclosed in FIGS. 1A-C, and especially asdisclosed in place in FIG. 2, although having the ends thereof cut atangles other than a right angle to the rafter edges, have a right anglebetween the end of the rafter and its faces, requiring only that thecutting tool be at the proper angle to the edges to make the cut.

[0052] Hip, valley, and jack rafters require that the cutting tool cutat compound angles, sometimes on the same workpiece and on the same endthereof:

[0053] 1. jack rafters, as disclosed in place in FIG. 2, and especiallyin FIG. 3, have at least one end thereof which is cut at an angle toboth the edges and the faces, this is a “compound” angle or “bevel” cut;

[0054] 2. hip rafters, as disclosed in FIG. 2., have at least one endwhich requires two cuts, both at compound angles to the faces and edges;and

[0055] valley rafters (not shown in place) have the same form as hiprafters, but are needed where two sloping roofs create a valley, andpresent the same problems in cutting as a hip rafter.

[0056]FIG. 4 discloses, in a view from the top, the overall structure ofthe wood-handling apparatus 100. The wood-handling apparatus 100preferably includes a live deck 102 for automatically supplyingworkpieces 104 to the infeed assembly 106. The infeed assembly 106supplies workpieces 104, one at a time, in a linear feed, to the cuttingassembly 200. The out-feed assembly 110 moves finished components 112away from the cutting assembly 108.

[0057] The cutting assembly 200 is shown in more detail in FIGS. 5A-5D.The cutting assembly 200 has at least one cutting blade 202, here shownas a circular saw blade. FIG. 4 shows an optimal arrangement of acutting assembly 200 with multiple cutting blades 201 and 202.

[0058] element 202 is mounted on saw-frame 204 and is movable in severaldirections. Element 202 is rotatable about its vertical axis V1,allowing motion of the element 202 as shown by arrow 1. The cuttingelement 202 is shown in its upright or home position 204 in FIG. 5B. Thecutting element 202 also moves vertically, allowing movement asindicated by the arrow Z1. The cutting element 202 is movabletransversely, across the workpiece 104, as indicated by arrow T1. Thecutting element 202 is finally rotatable about axis 16, allowingmovement as indicated by arrow 11. Movement of the workpiece along pathL is controlled by linear feed assembly 300, the infeed feeder 302 andoutfeed feeder 304 allowing lumber movement as indicated by arrow LM.

[0059] The practitioner will realize that the combination of movementsallowed by the feed assembly 300 and cutting assembly 200 will enablesimple and compound cuts to be made to a workpiece. The cutting assembly300 is in position for a compound cut in FIG. 5A.

[0060] The specific arrangement of the elements of the cutting assembly200 is not important as long as each of the relative motions of thecutting element 202 is achieved. In a preferred embodiment, the sawframe 204 is mounted to a stable object, such as a saw enclosure 206. Inthis case, the frame 204 is slidably mounted to transverse rails 208.The frame 204 is movable in the transverse direction, along arrow T1, bymovement along a ball-screw shaft (not shown) which interacts withaperture 210 in a manner known in the art. Piston-cylinder assembly 212controls the movement of the cutting element 202 in the vertical plane,Z1. Rotation of the cutting element 202 is controlled by servomotor andpulleys 214 allowing motion indicated by arrow 11. Similarly, rotationabout the vertical pivot, movement along line 1, is controlled by anactuator 217. Note that in the preferred embodiment, movement in thetransverse direction moves actuators 212, 214 and 216 along with all offrame 204. This arrangement can be modified as desired as long asmovement is allowed in the desired directions. Further, the preferredembodiment utilizes, convenient actuator mechanisms but any means knownin the art may be used to effect the various movements of the cuttingelements.

[0061] Linear movement of the workpiece is handled by the linear feeder300, namely the infeed feeder 302 and the outfeed feeder 304. Eachfeeder 302 and 304 has an upper component, 306 and 308, and a lowercomponent 310 and 312, respectively. In the preferred embodiment, theupper components, 306 and 308, are the drive components. The uppercomponents 306 and 308 are movable in the Z axis allowing the uppercomponents to clamp down on a workpiece to effectuate movement thereof.

[0062] The linear feeder 300 further comprises sensors (not shown) forsensing the presence of a workpiece and locating the end thereof. Use ofsuch sensors is known in the art. The upper components 306 and 308, seenin detail FIG. 6, have belts that press against the lumber and grip itagainst the lower components 310 and 312. The drive mechanism for thebelt is a servomotor with a measuring device or encoder, that measuresthe length of the workpiece as it feeds the lumber. Other drivemechanisms 324 and encoders 322 may be used, as are known in the art.The two units 302 and 304 are capable of working together, moving asingle workpiece at the same rate, or independently. Independentfunctionality is necessary since a workpiece may be cut and the upstreampiece 326 need to be moved back out of the way to allow movement ofdownstream piece 328 for further cutting. The finished segment 328 canthen be moved downstream to the out feed table 112. The feeder units 302and 304 act to maintain the workpiece stable during cutting.

[0063] Preferably any workpiece that extends at least half-way througheither feeder will be held steady enough to cut Pressure can be suppliedby springs, hydraulics or other known methods. The feed rolls shown arebelieved to provide better length measuring accuracy because they arenot subject to errors introduced by warped lumber or surfaceimperfections. Other roller, drive and measuring means may be used, suchas that described in U.S. Pat. No. 6,263,773 to McAdoo which is herebyincorporated for all purposes.

[0064] All of the motions of the saw elements and rollers are accuratelycontrolled by computer 400. The computer 400 determines the manner inwhich to position the saw blade, actuates all motion of the bladeelements and rollers, tracks the presence and length of workpieces, andoperates to cut workpieces to the required length and shape.

[0065] The cutting assembly and roller feed assemblies are operablyconnected to the computer 400 through appropriate electronics as areknown in the art. The computer enables the user to input the desiredlengths of wood product needed for a particular job. The computer mayoptimize the cuts made in the wood product through an appropriateprogram. Further, the computer controls the cutting unit and the drivingunit. The computer receives input signals from at least the positionsensors and encoders. The computer is operably connected to activate andcontrol the driver assembly and pressure assembly for positioning theworkpieces and the cutting unit. The computer receives input from themeasuring assembly to determine the length of the workpiece and todetermine the appropriate positioning of the workpiece in selecting thelocations of the cuts to be made. The computer may optimize the cuts inthe product by a method such as the one disclosed in U.S. Pat. No.5,44,635 to Blaine, which is incorporated herein by references.

[0066] It is possible to add a second cutting assembly 201 to increaseproductivity. The second cutting assembly 201 is similar to the first,200, but preferably below-mounted such that the cutting blade movesupward to execute a cut. The second cutting assembly 201 can be used toexecute a cut which the first assembly 200 is positioning itself.

[0067] The invention can also be combined with a marking assembly 500 asin known in the art, which can mark workpieces as to their size, shape,dimensions, or any other preferred indication.

[0068] The out feed system 110 can include a sorter, as seen in FIGS. 4and 7, as is known in the art, to dump the cut components into carts orother handling mechanisms. The use of sorters 600 and carts 602, withflip-up arms 604 to direct components is well-known in the art andsorters are commercially available from Alpine Engineered Products, Inc.

[0069] In use, the cutting assembly can cut all types of components,including those with compound or bevel cuts. For all cut sequences, asensor will detect the presence of a board and activate L1 to start theboard into the saw. A second sensor will detect the leading edge of theboard with sufficient precision to move the board into position forfirst cut. All subsequent cuts will be under the precise control of themotion control system, so no other adjustments will be needed until anew board is fed into the machine. The motion control system will trackand adjust for kerf material removed and end configuration resultingfrom previous cuts. As an example, FIG. 8 shows a component requiringmultiple cuts. With a single-head saw 200, the blade would set up,execute cut 1, reposition and execute cut 2, etc., for all four cuts. Ifa first 200 and a second 201 cutting unit are employed, unit 200 wouldposition and execute cut 1. Unit 201 would be positioning itself for cut2 while cut 1 is being made. Unit 201 would then execute cut 2 whileunit 200 positioned for cut 3, etc. Prior to cut 4, obviously, thelinear feeders would forward and position the workpiece for the finalcut. An infinite variety of cuts is possible.

[0070] One type of cut which the prior art machines cannot handle islong scarf cuts. FIG. 9 shows a detail of cutting for scarf cuts. In ascarf cut, the cut length, S, required is greater than the maximum cut Cof blade 202. For most cuts, cut length S will be less than maximum cutC. In a scarf cut, however, use of automated movement along axis T1 isemployed to make a cut as needed. The workpiece 104 is shown in place,engaged by feed roller assembly 302. The computer 400 positions thecutting blade 202 at the appropriate angle about axis 1, and along otheraxes as necessary. The cutting blade 202 is lowered, along vertical axisZ1, into cutting contact with the workpiece 104, engaging the workpieceto the maximum cut length C. The workpiece 104, via feed roller 302, isthen moved linearly while simultaneously the cutting blade 202 is movedalong the T1 axis, thereby translating the blade to mark scarf cut S.This type of cut is not possible without automated movement in the T1axis.

[0071] Practitioners will also note that automated movement along the T1axis allows the assembly to be used with varying widths of workpieces,e.g., 2, 4, 8 inches, without manual set up of the assembly or anyaccompanying downtime. This is another improvement offered by thepresent invention.

[0072] While the preferred embodiment of the invention has beendisclosed with reference to particular cutting enhancements, and methodsof operation thereof, it is to be understood that many changes in detailmay be made as a matter of engineering choice without departing from thespirit and scope of the invention as defined by the appended claims.

1. An apparatus for cutting a workpiece, the apparatus comprising: alinear feed assembly capable of automatically moving a workpiece alongits longitudinal axis; and an automated cutting assembly having at leastone cutting blade, the cutting blade rotatable about a pivot axis,movable along a vertical axis into and out of cutting contact with aworkpiece, and rotatable along a bevel axis, the apparatus thereby ableto cut the workpiece at a compound angle.
 2. An apparatus as in claim 1wherein the cutting blade is further automatically movable along atransverse axis.
 3. An apparatus as in claim 1 further comprising acomputer assembly for operating and controlling movement of the cuttingblade.
 4. An apparatus as in claim 1 wherein the linear feed assembly iscapable of moving workpieces up and downstream.
 5. An apparatus as inclaim 4 wherein the linear feed assembly comprises an upstream feedassembly and a downstream assembly.
 6. An apparatus as in claim 5wherein the upstream and downstream feed assemblies are operable toclamp and move workpieces, sense the presence or absence of a workpiece,and measure the length of a workpiece.
 7. An apparatus as in claim 1wherein the computer assembly further operates to optimize the use andcutting of workpieces.
 8. An apparatus as in claim 1 further comprisinga live feed assembly.
 9. An apparatus as in claim 1 further comprising asorter assembly for sorting cut workpieces.
 10. An apparatus as in claim1 further comprising a marking assembly.
 11. An apparatus for cutting aworkpiece, the apparatus comprising: a linear feed system for moving aworkpiece along its longitudinal axis; and a cutting assembly having acutter blade capable of cutting the workpiece at a compound cut tocreate a bevel cut on the workpiece.
 12. An apparatus as in 11 whereinthe cutting blade is further automatically movable along a transverseaxis thereby allowing a scarf cut on the workpiece.
 13. An apparatus asin claim 11 further comprising a computer assembly for operating andcontrolling movement of the cutting blade.
 14. An apparatus as in claim11 wherein the linear feed assembly is capable of moving workpieces upand downstream.
 15. An apparatus as in claim 14 wherein the feedassembly is operable to clamp and move workpieces, sense the presence orabsence of a workpiece, and measure the length of a workpiece.
 16. Anapparatus for cutting a workpiece, the apparatus comprising: a linearfeed assembly for moving a workpiece along its longitudinal axis; and acutting assembly having a cutting blade, the cutting blade having amaximum cut length and capable of automatically creating a scarf cutwherein the length of the scarf cut is greater than the cut length ofthe blade.
 17. An apparatus as in 16 wherein the cutting blade isfurther automatically movable along a transverse axis.
 18. An apparatusas in claim 16 wherein the linear feed assembly is capable of movingworkpieces up and downstream.
 19. An apparatus as in claim 16 whereinthe cutting blade is operable to automatically create a bevel cut on aworkpiece.
 20. A method for automatically cutting a workpiece, themethod comprising the steps of: moving a workpiece along itslongitudinal axis; positioning a cutting blade by rotating the bladeabout a vertical axis; positioning the cutting blade by rotating about abevel axis; and moving the blade into cutting contact with the workpiecethereby cutting the workpiece at a compound angle.
 21. A method as inclaim 20 further comprising the step of positioning the blade along atransverse axis.
 22. A method as in claim 20 further comprising the stepof moving the cutting blade along a transverse axis simultaneous tomoving the workpiece along its longitudinal axis, thereby creating ascarf cut.
 23. A method as in claim 20 further comprising the step ofsorting a finished workpiece.
 24. A method as in claim 20 furthercomprising marking the workpiece.